• Mass Spectrometry Letters
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• 제3권2호
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• pp.50-53
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• 2012

After success of sildenafil for the treatment of erectile dysfunction, a large number of its analogues have been approved from FDA. Recently, the illegal dietary supplements which include sildenafil, vardenafil, tadalafil, or analogues of these drugs as ingredient have been widely distributed. Therefore, the determination of the residue of synthetic phosphodiesterase- 5 (PDE-5) inhibitors in dietary supplements is highly required due to indiscriminate and unintentional overdose caused nausea, chest pains, fainting and irregular heartbeat. In this paper, we report a rapid and sensitive analytical method for the simultaneous determination of nine phosphodiesterase-5 inhibitors by liquid chromatography-high resolution mass spectrometry. The present method was found to be accurate and reproducible with 40 ${\mu}g$/g of the limit of quantification for the nine PDE-5 inhibitors. The developed method can be successfully applied to the analysis of the seven illegal dietary supplements.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
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• pp.81-84
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• 2002

The effects of the isoelectronic AI-doping of GaN grown by metal organic chemical vapor deposition were investigated for the first time using scanning electron microscopy (SEM), Hall measurements, photoluminescence (PL), and time-resolved PL. When a certain amount of Al was incorporated into the GaN films, the room temperature photoluminescence intensity of the films was approximately two orders larger than that of the undoped GaN. More importantly, the electron mobility significantly increased from 130 for the undoped sample to $500\textrm{cm}^2/Vs$ for the sample grown at a TMAl flow rate of $10{\mu}mol/min$, while the unintentional background concentration only increased slightly relative to the TMAl flow. The incorporation of Al as an isoelectronic dopant into GaN was easy during MOCVD growth and significantly improved the optical and electrical properties of the film. This was believed to result from a reduction in the dislocation-related non-radiative recombination centers or certain other defects due to the isoelectronic Al-doping.

• 한국임상수의학회지
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• 제32권2호
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• pp.215-217
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• 2015

국내경주마에서 검출되는 금지약물의 종류와 빈도는 보고된 바 없다. 본 연구의 목적은 국내 경마장에서 검출되는 금지약물의 종류와 검출빈도를 알아 보고자 2002년부터 2013년까지 국내 3개의 경마장에서 29,543 마리의 경주 전 경주마에서 채혈하였고, 경주 후에 3위 이내의 경주마와 재결지정마 91,482 마리에서 채뇨하여 효소면역분석법, 가스 크로마토그래프 질량분석계 그리고 액체 크로마토그래프 질량분석계를 이용하여 한국마사회 도핑검사소에서 검사하였다. 기간 중 경주전후 도핑 양성률은 각각 0.0030%, 0.0186%였으며, 경주 전에는 caffeine 그리고 경주 후에는 ketoprofen이 가장 많이 검출되었다. 약물의 약물동력적 및 약력학적 특성 때문에 혈액과 뇨의 결과가 달랐다고 생각된다. 그리고 재결위원의 조사결과, 금지약물검출은 오염된 사료 또는 깔짚에서 말에게 옮겨졌거나 출주예정마에 대한 말관리사의 혼란에서 비롯되었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제3권2호
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• pp.96-101
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• 2003

Direct evidence on the incorporation of high concentration of oxygen into undoped AlGaN layers for the AlGaN/GaN heterostuctures is provided by scanning photoemission microscopy using synchrotron radiation. In-situ annealing at $1000^{\circ}C$ resulted in a significant increase in the oxygen concentration at the AlGaN surface due to the predominant formation of Al-O bonds. The oxygen incorporation into the AlGaN layers resulting from the high reactivity of Al to oxygen can enhance the tunneling-assisted transport of electrons at the metal/AlGaN interface, leading to the reduction of the Schottky barrier height and the increase of the sheet carrier concentration near the AlGaN/GaN interface.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.237.1-237.1
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• 2016

Electrical properties of graphene-based field effect transistors (G-FETs) can be degraded in ambient conditions owing to physisorbed oxygen or water molecules on the graphene surface. Passivation technique is one of a fascinating strategy for fabrication of G-FETs, which allows to sustain electrical properties of graphene in the long term without disrupting its inherent properties: transparency, flexibility and thinness. Ironically, despite its importance in producing high performance graphene devices, this method has been much less studied compared to patterning or device fabrication processes. Here we report a novel surface passivation method by using atomically thin self-assembled alkane layers such as C18- NH2, C18-Br and C36 to prevent unintentional doping effects that can suppress the degradation of electrical properties. In each passivated device, we observe a shift in charge neutral point to near zero gate voltage and it maintains the device performance for 1 year. In addition, the fabricated PG-FETs on a plastic substrate with ion-gel gate dielectrics exhibit not only mechanical flexibility but also long-term stability in ambient conditions. Therefore, we believe that these highly transparent and ultra-thin passivation layers can become a promising candidate in a wide range of graphene based electronic applications.